1. Field of the Invention
This invention relates to a process for upgrading heavy high-sulfur hydrocarbonaceous materials, and more particularly to a process for making coke suitable for use as metallurgical coke from a low grade feedstock. The invention further provides for obtaining low-sulfur liquids and gases as additional products.
As the world's supply of high quality petroleum diminishes, there is an increasing interest in processes capable of handling the lower quality hydrocarbon sources. Many hydrocarbon reserves presently available or about to be available are of such low quality that they cannot be processed economically by conventional petroleum refining processes. These reserves typically are high-sulfur, low-gravity materials which are difficult to produce and difficult to handle after being produced.
2. The Prior Art
Several processes for producing useful products from heavy high-sulfur feedstocks have been proposed. One such process involves subjecting the material to a delayed coking operation. However, this results in a high-sulfur coke and high-sulfur byproducts, and further results in a substantial amount of high-sulfur coke fines. Thus, conventional delayed coking of heavy high-sulfur feedstocks results in a very undesirable products distribution.
It has also been proposed to process heavy high-sulfur feedstocks in a formcoking operation, followed by high temperature desulfurization of the resulting formcoke product. This provides a formcoke product which is acceptable as metallurgical coke (normally produced by coking special types of coal in coke ovens), but results in a relatively low coke yield, and produces an undesirably high amount of heavy high-sulfur byproduct which is difficult to desulfurize. Formcoking is a process in which heated carbonaceous particles are agglomerated by tumbling with a hydrocarbon binder to produce large solid particles suitable for use as metallurgical coke. Formcoking is described in detail in U.S. Pat. Nos. 3,073,751 and 3,117,918.
Various other schemes have been proposed for processing heavy high-sulfur feedstocks, but there has been a continuing need for a process which would provide an improved product distribution and which would not require exotic or unreliable techniques. Such a process is provided by the present invention.